This invention relates to diagnostic medical instruments and procedures, and more particularly to implantable devices and methods for monitoring physiological parameters.
The availability of a system and device capable of monitoring changes within any cell population of interest would be an important addition to the cancer treatment armamentarium and one that will fill a need by making available more precise knowledge of the most sensitive time(s) for treating a tumor cell population. This vital information could aid in the delivery of highly specific individual treatment regime rather than the empirical and somewhat generalized treatment plans of today.
The in vitro study of malignant cell populations have established important general principles by which clinical treatment protocols are developed. These principles have established differences between malignant and normal cell populations and have been employed in the treatment of malignant disease. There have been many attempts to exploit these differences, both in pre-clinical and clinical studies, in order to attempt to obtain total tumor cell kill and improved cure rates. One of the major obstacles in achieving this goal has been the difficulty in minimizing normal tissue toxicity while increasing tumor cell kill (therapeutic index). Thus, presently, most treatment strategies employ an empirical approach in the treatment of malignant disease. That is, the timing of delivery and dose of cytotoxic agents are guided more by the response and toxicity to normal tissue than by the effects on the malignant cell population. A major deficiency of this empirical approach is the lack of an efficient method or technique to provide accurate information on the dynamic changes during treatment (which can be extended over a long period of time) that occur within a malignant cell population. Making this invaluable information available to attending physicians can allow clinicians to exploit the revealed differences between malignant and normal cells, and hence improve the treatment procedures, to achieve better outcomes.
Much of the research in tumor biology has been involved in exploring the cellular, biochemical, and molecular difference between tumor and normal cells in order to improve the therapeutic index. Early cell kinetic studies revealed that cancer cells do not divide faster than normal cells, but rather a larger proportion of the cell population is dividing (Young et al., 1970). At that time, the failure to cure more tumors was attributed to a variation in growth characteristics. In the 1980""s, it was proposed that these failures were due to development of resistance of tumor cells through mutations of an unstable genome (Goldie et al., 1984). Later studies suggested that the mechanism for tumor cell survival rests on expression of a gene that codes for a specific protein that expels or extrudes the cytotoxic agents from the cell (Chaudhary et al., 1992). More recently, it has been suggested that resistance is related to dysregulation of the cell cycle which alters the rates of cell growth (Lowe et al., 1994). Additional factors associated with failure to eliminate or effect improved cure rate include hypoxic cell populations, cell proliferation variants, cell differentiation agents, and cell cycle sensitive stages. The ability to monitor these changes during and following any treatment could offer a more precise knowledge of the most sensitive portions of any cell population and aid in the delivery of a more individualized and less empirical or generalized treatment program.
There have been a number of attempts to study certain of the dynamic changes occurring within a cell population, but these attempts generally lack the ability to monitor the changes on a real time basis. Indeed, these methods typically provide information at one point in time and most are designed to provide information on one particular function or parameter. In addition, most of the conventional methods can be expensive as well as time consuming. This can be problematic for patients undergoing extended treatment periods typical of radiation and or drug or chemotherapy, especially when it is desirable to follow dynamic changes both during an active treatment and subsequent to the active treatment throughout a treatment period.
The most reliable current monitoring technique is the biopsy. A biopsy can be taken at any time and can provide significant amount of information. However, it is impractical to biopsy each day and, even if one could, the time delay created in performing the various tests on the sample means that the information received by the physician is not an accurate representation of the patient""s current condition. In addition to biopsy material, the radiological techniques of NMR and PET scanning can obtain, respectively, specific biological (cell cycle phase) and physiological (phosphorus) information, but both are sufficiently expensive that repetitive or daily information is rarely available. The radioactive labeling of specific antibodies or ligands is another available technique, but this method has many of the same problems noted above with the other assays.
In addition, over time, tumors progress through periods wherein they are less robust and, thus, potentially more susceptible to treatment by radiation or drug therapy. Providing a monitoring system which can continuously or semi-continuously monitor and potentially identify such a susceptible condition could provide welcome increases in tumor destruction rates. Further, especially for regionally targeted tumor treatment therapies, it can be difficult to ascertain whether the desired dose was received at the tumor site, and if so received, it can be difficult to assess its efficacy in a relatively non-invasive manner. Thus, there is a need for a monitoring system which can quantify and/or assess the localized or regional presence of a target drug.
Although much of the particular tumor-specific and/or internal systemic information which may definitively identify the most vulnerable tumor stage and, thus, the preferred active treatment period, is still relatively unsettled (as is the ultimate definitive cure or treatment protocol), various researchers have proposed several potentially important physiological and/or biological parameters such as oxygenation, pH, and cell proliferation which may relate to tumor vulnerability or susceptibility, and thus impact certain treatment strategies.
For example, in the article xe2x80x9cOxygen tension measurements of tumors growing in mice,xe2x80x9d it is proposed that it may be helpful to assess hypoxia in tumors during treatment. Adam et al., Int. J. Radiation Oncology Biol. Phys., Vol. 45, 1998, pp. 171-180. In addition, tumor hypoxia has been proposed to have an impact on the effectiveness of radiation therapy. See Seminars in Radiation Oncology, Vol. 8, 1998, pp. 141-142. Similarly, the authors of xe2x80x9cDevelopment of targeting hyperthermia on prostatic carcinoma and the role of hyperthermia in clinical treatmentxe2x80x9d note that there is a need for a way to assess temperature at the site of the tumor during therapy. Ueda et al., Jpn. J. Hyperthermic Oncol., Vol. 15 (supplement), 1999, pp. 18-19. Moreover, Robinson et al. opines that it is important to know the tumor oxygenation level and blood flow. See Robinson et al., xe2x80x9cMRI techniques for monitoring changes in tumor oxygenation in blood flow,xe2x80x9d Seminars in Radiation Oncology, Vol. 8, 1998, pp. 197-207. Unfortunately, tumor oxygenation can vary and there is evidence to suggest that tumor oxygenation is in a continuous state of flux. See Dewhirst, xe2x80x9cConcepts of oxygen transport at the microcirculatory level, xe2x80x9d Seminars in Radiation Oncology, Vol. 8, 1998, pp. 143-150. This flux makes a dynamic monitoring method important for identifying when the tumor oxygenation level is such that a more active treatment strategy may be desired. In addition, tumor pH has been suggested as an exploitable parameter for drug design for tumor treatments. See Leo E. Gerweck, xe2x80x9cTumor pH: Implications for Treatment and Novel Drug Designxe2x80x9d, 8 Seminars in Radiation Oncology No. 5, pp. 176-182 (July 1998).
In the past, various biotelemetry devices and implantable sensors have been proposed to monitor cardiac conditions or physiological parameters associated with glucose or temperature. For example, U.S. Pat. No. 5,791,344 to Schulman et al. entitled xe2x80x9cPatient Monitoring System,xe2x80x9d proposes a system to monitor the concentration of a substance in a subject""s blood wherein one enzymatic sensor is inserted into a patient to monitor glucose and then deliver insulin in response thereto. Similarly, PCT US98 05965 to Schulman et al, entitled xe2x80x9cSystem of Implantable Devices for Monitoring or Affecting Body Parameters,xe2x80x9d proposes using microsensors and/or microstimulators to sense glucose level, O2 content, temperature, etc. There are also a number of implantable medical devices and systems which monitor physiological data associated with the heart via telemetry. One example of this type of device is described in U.S. Pat. No. 5,720,771 to Snell entitled, xe2x80x9cMethod and Apparatus for Monitoring Physiological Data From an Implantable Medical Device.xe2x80x9d The contents of these applications are hereby incorporated by reference as if recited in full herein.
In addition, unlike conventional implanted sensors, tumor monitoring systems and/or sensors used to monitor tumors can be exposed to a relatively harsh environment during a treatment protocol or strategy which can extend over a period of weeks, or even months (such as applied heat, chemicals and/or radiation). Further, such a harsh environment, coupled with an extended treatment period, can affect the function of the device and thus, potentially corrupt the measurement data it generates.
In view of the foregoing, there remains a need for tumor monitoring systems and devices which can, inter alia, monitor the physiological and/or biological condition of a tumor during a treatment cycle to identify enhanced or favorable treatment windows to potentially increase in vivo treatment efficacy associated with such treatment.
It is therefore an object of the present invention to provide monitoring systems, methods, and associated devices which can dynamically monitor multiple tumor physiological and biological parameters and/or changes associated with tumors to identify enhanced or favorable treatment conditions to thereby establish a patient-specific treatment delivery time.
It is also an object of the present invention to provide a dynamic and/or semi-continuous (or even substantially continuous) tumor monitoring system which can be remotely monitored on an ongoing basis during treatment.
It is an additional object of the present invention to provide an implantable cancerous tumor sensor system which is cost-effective and which can provide sufficient ongoing, and preferably substantially real-time, information pertaining to the physiological and/or biological condition of the tumor during a treatment period in a way which provides the information to the physician to assist in therapeutic decisions.
It is yet another object of the present invention to provide a tumor monitoring system which can provide real-time information regarding cancerous tumor physiology as an adjunct to therapy.
It is an additional object of the present invention to provide a cancerous tumor monitoring system which can provide clinically effective regionally specific data representative of the dynamic effects of cytotoxic agents on cell populations during an extended treatment period.
It is another object of the present invention to provide an implantable oxygen sensor configuration which is particularly suitable for monitoring the oxygenation and/or pH level in a tumor.
It is yet another object of the present invention to provide system related sensors and computer program products for identifying when a tumor exhibits potential vulnerability or susceptibility based on data associated with an in vivo in situ sensor which provides measurements of parameters associated with a tumor.
It is another object of the present invention to provide a method of remotely monitoring parameters associated with a patient""s cancerous tumor physiology and alerting a clinician of the presence of a condition indicating a favorable treatment period or the need for other evaluation or adjustment in an ongoing planned treatment strategy.
It is an additional object of the present invention to provide a system for monitoring tumors which can indicate (in substantially real time) whether conditions are favorable or unfavorable for an active treatment such as drug delivery, hyperthermia, chemotherapy, or radiation therapy.
It is still another object of the present invention to provide a system or computer program product for analyzing a plurality of measurements generated by at least one implanted sensor and analyzing the measurements and identifying the presence or absence of one or more predetermined conditions associated with the measurements to alert the clinician of the existence of a potentially vulnerable and desired treatment phase for a tumor.
These and other objects of the present invention are provided by a bio-telemetry based tumor monitoring system with in vivo, in situ sensors positioned to monitor multiple selected parameters representative of the status of a tumor or tumors in a subject.
More particularly, a first aspect of the present invention is a method of monitoring and evaluating the status of a tumor undergoing treatment. The method includes the steps of monitoring in vivo at least one physiological parameter associated with a tumor in a subject undergoing treatment with an in situ sensor. Data associated with at least one monitored physiological parameter is transmitted from an in situ positioned sensor to a receiver external of the subject. The transmitted data is analyzed to determine how the tumor is responding to treatment. Additional data is transmitted and analyzed periodically at a plurality of sequential points in time, and a tumor treatment strategy is evaluated based on the analyzing step.
In a preferred embodiment, the transmitting and analyzing steps are repeated sufficiently often (such as at least every 24 hours, and more preferably at least hourly, at least during particular time segments of treatment) to track variation in at least one monitored parameter and thereby assess the behavior of the tumor over time. It is also preferred that at least one parameter is a plurality of parameters, and that the analyzing step defines a plurality of test conditions associated with the monitored parameters to evaluate the treatment corresponding to the condition of the tumor (such as the efficacy of treatment or the presence or absence of favorable indices of treatment). If the transmitted data satisfies at least one test condition related to the monitored physiological parameters, a clinician can then be alerted as to the presence of at least one of a favorable and unfavorable treatment window for delivering a subsequent active treatment to the tumor. Preferably, the favorable treatment window corresponds to the identification of a tumor susceptibility or vulnerability phase.
It is also preferred that the transmitting step comprises transmitting data from the home site of the patient to a remote clinical site thereby allowing real-time remote dynamic monitoring of the physiological parameter. Further, it is also preferred that the transmitting step is repeated temporally proximate to a subsequent active treatment delivery time to provide real-time information regarding the desirability of the timing of a planned treatment or the efficacy of a delivered treatment.
Another aspect of the present invention is directed to a tumor monitoring system for evaluating the efficacy of radiation or drug treatment and/or identifying enhanced or favorable active treatment windows. The system comprises at least one sensor unit comprising a plurality of sensor elements and associated sensor electronics configured for in vivo, in situ contact with a cancerous tumor in a subject undergoing treatment. The sensor elements are configured to sense a plurality of different physiological parameters associated with the tumor and wirelessly transmit the sensed data. The sensor units have an implanted service life of at least about 6-10 weeks, and more preferably at least about 8-12 weeks. The system also includes a remote receiver in wireless communication with the at least one sensor unit, and is configured to receive the transmitted sensor data. The receiver is positioned external to the subject.
The system also preferably includes a data processor configured to receive the transmitted data including computer program code means for reviewing and adjusting the received data to correct for variations attributed to environmental exposure in the subject.
An additional aspect of the present invention is directed to a computer program product for monitoring and analyzing the condition of a tumor undergoing treatment. The computer program product comprises a computer readable storage medium having computer readable program code means embodied in the medium. The computer-readable program code means comprises computer readable program code means for commencing a first wireless data transmission from an in situ sensor with at least one sensor element, where the at least one sensor element is positioned in a subject proximate to a tumor undergoing treatment to monitor at least one physiological or biological parameter of the tumor, and the data transmission includes data corresponding to the output of the at least one sensor element. The product also includes computer readable program code means for commencing a second wireless data transmission from the in situ sensor temporally separate from the first wireless data transmission and computer readable program code means for tracking variation between the first and second data transmissions to provide a dynamic behavioral model of the tumor""s response to the treatment.
Preferably, the computer program product further comprises computer readable program code means to evaluate the efficacy of the treatment corresponding to either of a predetermined absolute value or relative change of the monitored at least one physiological parameter over time. It is also preferred that the computer program product further comprises computer readable program code means for commencing ongoing periodic data transmissions over a predetermined (and/or adaptively determined or scheduled) time period, and computer readable program code means for analyzing the data transmissions to identify potential enhanced or favorable active treatment opportunities.
Advantageously, and in contrast to the empirical treatment strategies employed in the past to schedule active treatments (such as chemotherapy or radiation therapy), the present invention now allows targeted tumor treatment directed by the response or behavior of the malignant cells of a tumor itself as well as the response of the normal cells proximate to the tumor(s). Further, the present invention allows both real-time treatment information during active therapy sessions as well as dynamic tracking during non-active periods. Indeed, a patient can transmit or communicate the monitored parameters on a regular basis with a clinical site via implantable telemetry based sensing devices and home base receivers (such as even multiple times in a 24 hour period) in a relatively cost-efficient manner. This ongoing communication can download real-time information regarding the state of the tumor to a clinical monitoring station. This information can then be analyzed by computer programs to identify or evaluate oncology treatment strategies associated with a particular tumor type. For example, the dynamic tracking can identify relative changes in the tumor and/or absolute values associated with a positive or negative reaction to therapy. This reaction tracking can allow for more proactive therapeutic decisions based on the tumor""s response to the treatment. The dynamic tracking can also be used to identify the onset or predict a potentially vulnerable phase of a tumor to allow more effective timing of treatment regimes corresponding to the actual behavior of the tumor. Preferably, the sensors are positioned at more than one location in the tumor (surface and at a penetration depth), and more preferably at more than one region (over the volume or surface area) associated with the tumor(s) to be able to quantify the tumor""s overall response to therapy.
Advantageously, the systems, methods, and devices of the present invention can monitor, in real time and/or dynamically, specific indices associated with tumor physiology making them available for immediate use in treatment decisions. Hence, the instant invention can lead to more definitive and patient-specific treatment protocols, increase tumor response, decrease treatment morbidity, and improve and/or replace assays predicting tumor response, resistance and sensitivity. The present invention can provide information not previously readily available for commercial clinical applications which will likely open new fields of research and therapeutics. The device is particularly suitable for oncology applications.